Conventionally, used are apparatuses for recognizing a character string printed on a surface of a medium such as a check. For example, known is a character recognition apparatus in which a character part is retrieved out of a binarized image datum, and the character part is segmented along a circumscribing rectangular frame; and then, an amount of characteristic is extracted from a obtained character pattern, and a level of similarity is calculated between a characteristic vector of an input pattern and a reference vector of each character in a characteristic dictionary in such a way that a candidate character is chosen according to the magnitude of the similarity.
In a character segmenting operation of a character recognition apparatus, a position in a direction perpendicular to a character string is detected according to projection data of image data in the direction of the character string. Then, according to the detection, while a detecting position being shifted in the direction of the character string, projection of the image data in the direction perpendicular to the character string is calculated. Subsequently, a position having its obtained projection data exceeding a predetermined threshold is detected as a segmenting position of characters constituting the character string.
The applicant discloses a technology in which the position of the character string in a vertical direction perpendicular to the direction of the character string is detected in the operation of segmenting a character from the image data according to the horizontal projection data of the image data in the direction of the character string; according to the detection, while the detecting position being shifted in the direction of the character string, the vertical projection of the image data in the vertical direction is calculated; and then a position having its vertical projection data, obtained in that way, exceeding a predetermined threshold is detected as a segmenting position of characters constituting the character string; in the meantime, a segmenting position of the characters included in the character string is detected according to either threshold of a first threshold and a second threshold, as the predetermined threshold, the first threshold being determined in accordance with the number of pixels between both ends of the character string detected from the vertical projection data, and the second threshold being determined in accordance with the number of the characters constituting the character string, out of positive peak values included in the vertical projection data (for example, refer to Patent Document 1).